The present invention is directed to a tamperproof hydrant lock with a controlled shock absorber. In particular, the invention is directed to a tamperproof hydrant lock with a controlled shock absorber comprising a series of parts which are easily assembled in combination with a subsisting fire hydrant. The lock is relatively inexpensive, simple and convenient to assemble, and is believed to be the first truly tamperproof lock of its kind. The lock can be sold in kit form to retrofit a subsisting hydrant.
There has been a long felt need for a tamperproof lock for a fire hydrant. The unauthorized use of fire hydrants has led to staggering losses of money and man-hours in attending to the readjustment of vandalized fire hydrants and their repair. Moreover, the unauthorized use of a fire hydrant may be extremely dangerous. Municipal reservoirs generally have a limited capacity to cope with the drainage posed by continuously open fire hydrants. Additionally, a vandalized hydrant may prove inoperable for emergency use.
Many attempts have been made to design a fire hydrant which is vandalproof. In general, these involve fresh designs for the entire hydrant and replacement of subsisting hydrants with completely new ones. Subsisting fire hydrants cannot be retrofitted conveniently to implement the proposed designs. Furthermore, the manufacture of a completely new fire hydrant is relatively costly. On a practical basis, these factors may render such designs useless. Accordingly, the vital problem of rendering subsisting fire hydrants tamperproof remains unsolved.
Apart from the practicalities of time and expense in implementing the designs of the prior art is the effectiveness of the design for the intended purpose: rendering the fire hydrant truly tamperproof. In general, prior art designs tend to be rather intricate and succeed only in making the fire hydrant somewhat more difficult to vandalize without actually achieving the goal of a fire hydrant which, for all intents and purposes, cannot be operated by unauthorized parties.
Various designs for valve locks and actuating mechanisms are disclosed in U.S. Pat. Nos. 3,070,115, 3,290,003, 3,361,154, 3,453,897, 3,456,679, 3,532,108, 3,532,109, 3,543,777, and 3,672,393. A fire hydrant with tamperproof features is disclosed in U.S. Pat. No. 3,532,109. The patent is directed to the new design of a bonnet, operating shaft and a screw jack or operating mechanism. The operating shaft is reciprocable within a bushing mounted within the interior of the bonnet. The end of the operating shaft and the bushing are accessible to the exterior of the bonnet. The bonnet is provided with a pair of holes which penetrate to the bushing surface. The screw jack includes a pair of spring-urged latches which are snapped apart and then positioned in the holes to retain the screw jack in an operative position.
Since the bushing is exposed, it apparently can be rotated, unscrewed and removed from the hydrant, providing access to the entire operating shaft. The exposed operating shaft might then be rotated and removed from the hydrant. In addition, once the bushing is removed, the interior of the housing is completely exposed and could be jammed with foreign matter and otherwise vandalized to render the hydrant inoperative.
Since the pair of bonnet holes penetrate to the bushing, the bushing could be deformed or otherwise vandalized to preclude operation of the shaft.
While the screw jack is mounted on the bonnet, the latches could be pried apart by an unauthorized party and the screw jack removed therefrom. Accordingly, the attendance of an authorized party would be required to continuously monitor the screw jack while it is mounted on the bonnet.
An advantage of the present invention is that it is truly tamperproof.
Another advantage of the invention is that it can be sold in kit form and used to retrofit a subsisting fire hydrant.
Another advantage of the invention is that the bulk of the components of a subsisting fire hydrant need not be re-designed or modified to implement the tamperproof lock.
Another advantage of the invention is that the operating rod is inaccessible to the bonnet exterior.
Another advantage of the invention is that the accessible portion of the lock is mechanically separated from the operating portion thereof so that the accessible portion of the lock can be hammered, chiseled or rotated without affecting the operating portion thereof.
Another advantage of the invention is that the means for exerting a force along the axis of the operating rod to reciprocate the rod can be locked on the hydrant bonnet and cannot be removed therefrom except by authorized personnel.
A further advantage of the invention is that it prevents sudden closing of the hydrant valve thereby avoiding water hammer and rupture of the water mains.
A still further advantage of the invention is that it provides controlled gradual opening and closing of the hydrant valve over predictable delay intervals of time.
Other advantages appear hereinafter.